Temporal trend and influencing factors of high-risk pregnancy in China: a nationwide longitudinal analysis.

High-risk pregnancy was a major challenge to sustainably reduce maternal mortality rate to achieve the Sustainable Development Goals in China. This study aimed to analyze the temporal trend of high-risk pregnancy rate in China and to explore the influence of socioeconomic factors. Panel data of 31 provinces in China from 2002 to 2016 were extracted from the China Statistical Yearbooks and Health Statistical Yearbooks. We firstly adapted JoinPoint regression model to describe the temporal trend of high-risk pregnancy rate. Then, an auto-regressive integrated moving average model was built to predict high-risk pregnancy rate from 2017 to 2030. Finally, a linear mixed model was employed to evaluate the impact of socioeconomic factors on high-risk pregnancy rate at the provincial level. The high-risk pregnancy rate increased substantially with an average annual percent change of 6.06% (95% CI: 5.70, 6.51%) from 1996 to 2016 in China. Except Tibet, the high-risk pregnancy rate of other 30 provinces all presented an upward trend with an average annual percent change ranging from 1.86% (95% CI: 1.47, 2.35%) to 11.15% (95% CI: 9.22, 13.10%). The predicted high-risk pregnancy rate would up to 38.76% (95% CI: 31.66, 45.85%) in 2030 in China. The number of hospital beds per 1,000 population was negatively associated with high-risk pregnancy rate (β = -0.0476, 95% CI: -0.0767, -0.0185). While female illiteracy and GRP per capita were positively correlated with high-risk pregnancy rate, the coefficient was 0.0127 (95% CI: 0.0050, 0.0203) and 0.1717 (95% CI: -0.0205, 0.3639) respectively. The high-risk pregnancy ratio in China has been increasing and sustains an upward trend, posing great challenge to maternal health improvement in China. Healthcare resources and other socioeconomic factors have significant effect on high-risk pregnant rate, such findings can provide evidence-based implications for long-term policy-making in healthcare resource allocation, urban development and gender equality. Constant efforts by all society should be made to enhance maternal health to achieve the goals of the Sustainable Development Goals and Healthy China 2030.